Scientists have found a small piece of zircon crystal on a sheep ranch in Western Australia that dates back to 4.4 billion years. The crystal is the oldest known piece ever found, according to them.
Zircons are part of the Earth's crust, which is found in igneous, sedimentary and metamorphic rocks.
The study was conducted using a technique called atom-probe tomography, which in conjunction with secondary ion mass spectrometry, allowed scientists to accurately begin the age and thermal history of the zircon by determining mass of individual atoms of lead in the sample.
"It's always blown my mind. I mean, to collect samples that were on a beach 3 billion years ago- and to find crystals that were more than a billion years older than the beach- is just really surprising and wonderful", according to John Valley, a geochemist at the University of Wisconsin, Madison.
Confirmation of the zircon age holds huge implications for models of elderly Earth. The trace elements in the oldest zircons from Australia's Jack Hills range suggest that they came from granite-like rocks such as tonalite or granodiorite. This implies that the Earth cooled much quickly for surface water and rocks just 100 million years after the moon impact, the huge collision that formed the Earth-moon system
"This confirms our view of how the Earth cooled and became habitable. This may also help us understand how other habitable planets would form. The study reinforces our conclusion that Earth had a hydrosphere before 4.3 billion years ago and possibly life not long after," Economic Times quoted Valley.
The details of the findings have been published in the Nature Geoscience Journal.